EDIT:
Kernel is now 2.6.26 (vs 2.6.22 on Kindle 2). MarioMX (Kindle 2's system) no longer has a config file (don't know how similar the new arch is, or what the codename is).
EDIT 2:
The config files Amazon added are:
imx21ads_defconfig
imx27ads_defconfig
imx31_3stack_defconfig
imx31ads_defconfig
imx35_3stack_defconfig
imx35_luigi_defconfig
imx35evb_defconfig
imx37_3stack_defconfig
imx51_3stack_defconfig
Could "Luigi" be the new Kindle's internel name?
Ok, googling all these file names gives results except "imx35_luigi_defconfig", so it must be new to the world. Could the Kindle 3 be a MX35 machine?
EDIT 3:
Yup, Luigi is the new Kindle, and iMX35 is it's arch. Also, the root fs is now 256MB, rather then 128MB. And, as expected the new kernel supports wireless & netfilter (for wireless functions). One day, I'll try to compile this kernel for now-old Kindle 2. Wifi Card seems to have an "ATHEROS AR6000" chip. USB Networking is still in the kernel (not sure about firmware though).
EDIT 4:
There's SD card support is in the kernel, but unsure if it's in the hardware.
Edit 5:
Kindle 2 support is gone (at least in this source release of the kernel). Either amazon will release a different (older) version of the kernel for kindle 2 3.0, or kindle 2 won't get 3.0.